Dental or other furnace or oven



March 18 1924n GL M. HOLLENEACZK DENTAL 0R OTHER FURNACE OR OVEN Filed June ze 1918 j closed in the drawing are Patented lli/lar. i8, 1924.

'irse STATES V1,487,330 PATENT omas.

GEORGE M. HOLLENBAGK, 0F LEWISTOW N, MONTANA.

DENTAL OR OTHER FURNACE 0R OVEN. i

Application filed June 29, 1918. Serial No. 242,521.

This invention relates to dental and other furnaces and ovens, and it has for its object to provide an improved device or improved apparatus of the character stated,

which will be superior in point of relativo inexpensiveness and simplicity, taken in connection with positiveness and reliability and precise accuracy in performance and operation, convenience in use, and length of life or durability; and which will be generally superior in eiiiciency and servicea-y bility.

With the above and other objects in View,

the invention consists in the novel and use-V ful provision, formation, association, combination, relative arrangement and mode of operation and operative control of parts, members and features, all as hereinafter described, shown in the drawing, and finally pointed out in claim.

The drawing is a central vertical sectional view of an improved device or improved apparatus embodying the invention, parts being shown in elevation for clearne'ss `0f illustration. f

rllie various parts and features as d isdesignated by reference characters. j

Referring with particularity to the drawing, the improved furnace or oven for dental or other purposes which is disclosed therein as embodying and exemplifying the invention, is provided with or formed to provide a working chamber A, within which is disposed the object, article or work to which heat is to be applied, or which is to be subjected to thermal action, the heat being rso applied or provided by or at a sourceof heat units B, the latter 4being `preferably disposed beneath the chamber A and its bottom member 2. The chamber A and heating v chamber b within which the source of heat B is disposed, are both conveniently and inexpensively provided within a `common casing 3, which is shown as cylindrical, the lower portion of such casing being cut out or notched `to provide legs or supports` 4",

admitting air to the'heating chamber for the purpose of supporting combustion therein, depending upon the nature and character of the heat producing means B. The working chamber A isv sealed 0H from the heating chamber b by the bottom member y2 which is a circular plate or diaphragm eX- tending transversel 'of yand within the casing 3. Beneath this plate or diaphragm 2 and between it and the source of heat B is disposed a baffle plate or heat distributor 4 which l is preferably connected with such plate or diaphragm 2 andfdepends from it, producing an openL air space orchamber 5 between the main body of such distributor and the plate'2, and of an area coincident with the central portion of the diaphragm 2, and coincident with as much of the area of said diaphragm as the proper distribution of the heat may require. As shown in the drawing, the distributor or baffle plate 4 is, and may conveniently be, suspended from the bottom plate 2 by a series of lingers 4a which, by means of hooked marginal portions, 4b, take into openings in the bottom plate 2. Such series of lingers 4a are alternated with open spaces 4, to open up communication of the space between such plate 4 and such plate 2 and destroy the dead air space which would otherwise exist. y l

The working chamber A is provided with a closure C, which may consist of a cap 6 extending over and Afitting the mouth of the chamber A, and having an annular marginal flange 6a, overlapping the side wall of the chamber A or of that portion of the casing 3 which constitutes the lateral walls of such chamber, Fixed to such closure plate 6, and projecting both above and beneath the same, is a temperature-indicating device D,which may consist of a thermomstel` with Fahrenheit or other readings, and preferably has its bulb immersed in a mercury bath confined within a' container d which is disposed in contact with the diaphragm 2 directly above the baiile or distributor plate 4. The portion of the `ther,-

mometer having the usual'readings projects above the closure plate 6, so that when the closure is in position to seal the mouth of the chamber kA the readings of the thermometer may readily be noted to determine thethermal condition of the working chamber.

icc

The source of heat B is specifically disclosed as comprising electrica'l'resistance in a coil 7 disposed Within the heating chamber b and adapted to be supplied With electrical energy through circuit Wires i8, leading to a suitable source of electrical energy, and included Within the circuit of such iviresl 8 and coil 7 are further circuit Wires 9 leading to and in circuit with a thermostatic device 113of any preferred organization, and which ,has its` heatfsensitivejelement `e. disposedr wit-hin' the, Werking' chamber A. By means of suchv thermostatfic" device, and

its co-action With anjelectriclal contact 1Q' Within such Workingy chamber, a ndf, ri1,.0ir' cuit With thewc'rcuitl Wiresl 9, the :energ-iz,a` tion of the resistance coi' 17imaybecon` Oued responsive' to temperatures in the) v so), the Work' vor ,object or'rarticle to beheated is placed vvithinthe chamber,,A5,and.V the? closure C With its temperature-indicating device D is placed over` saidnhamber so `asVv to enclose thesame with the'vvorktherein. The source of lheat Bv lis thenlj rendered f effective, and either vvith'or' without theauto;`^

matically controlling thermostatic device E or its equivalent or substitute, imparts its heat units' to, the'l chamber fiflaniihthe' Worky therein, throllg'h 4 the diaphragm 9.1i bottem,v plate 2, the battle: plate or' di`stributerl plate 4 servingto preventa concentration:

ofy heat .applcationudirectlyl,at thecenter of the chamber A or at the point",'of,dispositionh thereinv of the heat-responsive bulb ofthe: thermometer. Ofy ,course in the use of' they resistance coil 7 such heat-concentration' is less pronounced than in the use,'for instance, of a Bunsen burner, disposed centrally of the chamber b, inthe manner indicated by dotted lines in the drawing. ItWill be understood that such baffle or distributor utilized vvhen ,necessaryto' cause an even diffusion ,of theheatjrom such source of heat B as may beemployed, and itseven dis` v tribution throughout,v the l Working chamber A, Whi'ch as indicatedmay havejan asbestos or likelin'ing, atits sides .and'tcp. Asjheat rises in the; chamber Athe indicatingyy coll/ umn in the thermometerv or heat-indicating'` device D ascends, and when the proper reading has been reached in this manner, the production of heat is automatically discontinued, as by a thermostatic device, or any equivalent or substitute thereof, and suchheat production is re-established, in intermittent action, as requisite to maintain a constant temperature Within the chamber A. Or, the production of heat may be terminated and renewed voluntarily, Where no such automatic controlling means, such as E, isemployed.'V yThis operation is carried on, namely, this maintenance of an accurately;` ,constant temperature in the Working', chamberA, asflong as thevvor'k, therein isjj subjected to thermal' action'. In the use,V of the apparatus as a dental oven or furnace, vvevvilll assume that the Work in the chamberI A comprises a metallic flask containing a Wax rinlay pattern investedV in aj hardened pljasftic substance, The constantly 1naintainedjtemperaturein the Working chamber isv effective to burn out andl eliminatev the vvaX c ontained" y in the pattern in the surrounding substance, leaving a mold to be utilized'in'casting the inlay. v This is but one'v illustrationof the use of this apparatus, and its'highly advantageous utility in the provi-l sion of a' Workingv chamber A in which a definite temperature is to be preciselyand accurately maintained. It has been Afound in practice that unless such constant temperature is maintained', for instance in the productionof aninlay mold, as described,-

thatjthe' initially plastic material in which the mold has to` bey formed by the burning outof the Wax, becomes so over-expanded'or heat-affected, that the subsequentl shrinkage fails l,to restore the Wax-containing cavity,

vvhi'ch' becomes the mold, to its normal and proper formation and dimensions, thus producing a distortion, and error of formation whichV in turn produces an incorrectly shapf en and proportionedinlay. It Will'be readiunderstood that in Work of this character the slightest departure from correct dimensions and conformation will be fatal.

Itvvill bemanifest that manyvariations,v

modifications', changes and departuresl may be made, in adapting the invention to varying conditions" of use and service, and in' practicing the invention, 4under varying conditions,A and vfor different purposes, in de'- partures from the specific disclosures of the.

drawing/and the preceding description, and statement of operation and mode of use, vvithoutdeparting from the true spirit of the `invention and a fair interpretation thereof. v

Having thus disclosed my invention', IV claim and1 desire to secure by Letters Pati ent: 1

In ay dental oven, the combination with aA chambered;Work-holding member, of means .said member in elevation, .al clo';

sure for said member, and'means for applying heat to said member; there being a at ature within the chambered work-holdingv heat distributing plate pendent from the member is denoted exteriorly of the oven. base of said work-holding member and in- In testimony whereof, I have signed my terposed between the source of heat and base y name to this specification in the presence of of thebwork-holdilg Crnembr; said oven liketwo subscribing witnesses.

wise eing provi e wit a thermometer mounted upon said closure and having its GEORGE M' HOLLENBACK heat sensitive element within the chamber Witnesses: of the work-holding member and in Contact RAYMOND Ivins BLAKESLEE, 10 with the base thereof whereby the temper- J. SHUTT. 

